Google, Yahoo, AOL and Microsoft are among eight internet companies stepping up their efforts against online piracy.

As part of the new measures, copyright holders from the creative industries can alert search engine firms if their adverts appear on illegitimate websites, allowing the likes of Google to take action without altering its search results.

Websites offering illegal downloads attract high levels of traffic, with the advertising this attracts providing an essential source of income. Targeting this revenue stream would strike a damaging blow to internet piracy.

US Intellectual Property Enforcement coordinator Victoria Espinel and advertising body the Interactive Advertising Bureau (IAB) teamed up to launch the initiative in a bid to combat copyright infringement and counterfeiting online.

"We believe that this is a positive step and that such efforts can have a significant impact on reducing online piracy and counterfeiting," said Espinel in a statement.

She went on to describe the scheme as "a good example of how the public and private sector can work to combat piracy and counterfeiting while protecting and, in fact, further encourage the innovation made possible by an open Internet."